Marker control apparatus for group selectors



April 10, 1951 D. P. LONG 9 5 MARKER CONTROL APPARATUS FOR GROUP SELECTORS Filed April 25, 1946 2 Sheets-Sheet 1 haNY :1 llurney Aprifi E0, 1951 D. P. LONG MARKER CONTROL *APPARATUS FOR GROUP SELECTORS Filed April 25, 1946 2 Sheets Sheet 2 a 0 00 r o n o n n n 0. m m 3i Q .fi q Q Inventor DOUGLAS PERCY LONG Attorney k ww 513 5% 2 Patented Apr. 10, 1951 UNITED STATES PATENT OFFICE MARKER CONTROLAPPARATUS FOR GROUP SELECTORS Douglas Percy Long, Chislehurst, England, as-

signor to Siemens Brothers & Co. Limited, London, England, a British company Application April 25, 1946, Serial No. 664,962 In Great Britain May 4, 1945 6 Claims.

1 This invention relates to automatic telephone systems and more particularly to systems in which a group of outlets from a selectin switch of one rank to a selecting switch of another rank" V with one arc, and another, electrically connected sets of outlet groups, the selection of a particular outlet group of a set being effected by means of a marking applied thereto consequent on the receipt of a train of impulses.

In the present invention the marking of an outlet group is efiected over one or other of a pair of contact-making members of a marking device, the particular contact-making member to be used depending on the receipt or non-receipt of the differentiating signal. The contact-making members may be wipers of the same stepping switch or Wipers of difierent stepping switches. The differentiating signal may effect discrimination between odd and even digits of the same digit place so that, in effect one wiper or stepping switch serves for marking odd digits and the other even digits. will be cross-connected accordingly to the arcs of the selecting switch. If selection is, as is usual, on a decimal basis, the marking switches may have 10 outlets each. The marking device is also used to control the transmission of a differentiating signal to the subsequent rank of switches and here again difierentiation is conveniently effected according to whether the digit received at the Arcs associated with these wipers to itbut staggered along the switch shaft and set at 180 to the first being associated with another arc, at the commencement of which the said predetermined contact position is situated. The further relay is conveniently arranged to be released by differential action in the test circuit over the predetermined contact position.

If two marking switches are used, a contact of the signal receiving relay or an auxiliary thereto is connected in the impulse repeating circuit in order to direct the received impulses to the magnet of the appropriate marking switch, the circuit including. a low resistance winding of the i use, the circuits being connected up by the operaselecting switch is odd or even. The differentiating signal may take the form of a potential applied temporarily to one of the speaking wires,

whereby a relay connected to this wire in the subsequent switch at the time of seizure is short-circuited and prevented from operating. This potential may be applied over contacts of the marking device, in either the odd or even contact positions. Other sets of wipers of the marking device may be used to effect other switching operations such as wiper switching, and the operation of overflow meters. Other forms of difierentiation may be employed.

If the signal receiving relay is operated, it may look up and bring about the operation of a fur ther relay to efiect the driving of the switch wipers to a predetermined contact position. This position may be at the commencement of an arc of contacts reached by the wiper after a rotation of 180, one wiper of a pair being associated tion of the test relay.

A 200-out1et selecting switch using arcs of 50 outlets each requires a wiper selecting operation. This may be performed by a relay operated over contacts of the markingdevice in appropriate positions: A group of outlets may also be disposed some in one set of arcs and some in another and it may be arranged that if those in the first are are all found busy a wiper switching operation takes place whereby those'in the other are are tested. To this. end the early contacts of a split group are vconnected to early contacts, preferably at the commencement of the first arc of a pair of successively swept arcs with the Wiper switching relay operated and the later contacts of the group are connected to the later contacts, preferably at the end of the second arc of the successively swept pair with the wiper switching relay released. For this purpose the wiper switching relay may be cross connected over appropriate contacts of the marking device to a wire that is earthed over a make contact of a slow releasing relay operated on receipt of the first impulse of a train and released after the end of the train following a period of delay. The delayed release of this relay gives time for the selecting switch to search the early contacts of the split group before the circuit of the wiper switching relay is opened to connect up the'wipers associated with the other set of arcs. 3

The marking device and control relays may be 'outlets. electric motor underthe control of a magnet,

assembled in a common control circuit and by the use of two marking switches and by providing the arcs of the marking switches in pairs to give two independent sets of markings, selecting switches in two different numerical groups may be served by the common control circuit.

The incoming speaking wires may be normally connected over back contacts of a last contact relay to a low impedance impulse receiving relay and a signal receiving relay and over the front contacts of the last contact relay to a high impedance relay, a contact of one of these latter relays, when operated holding the impulse receiving relay. The high impedance relay may be utilised to repeat in a balanced circuit a tone fed through a third winding.

The arrangements of the invention are especially applicable to selecting switches of the high speed uniselector type, such as the motor driven uniselector.

Reference will now be had to the accompanying drawings which show'by way of example an embodiment of the invention.

' The drawings show, in Fig. 1, the circuit of a group selector and in Fig. 2 a common control circuit for the control of a group of selectors of the kind shown in Fig. l. The group selector illustrated is a single-motion motor-driven switch having 200 outlets, access to one hundred outlets being had over back contacts of a wiper switching relay and access to the other hundred outlets being had over front contacts of the wiper switching relay. The contact bank of the selector comprises 16 arcs of 52 contacts each-the arcs being paired, the two arcs of a pair being traversedrespectively by the two ends of a wiper in'succe'ssion, one end of the wiper entering the bank after the other end of the'wiper has left it. The arcs over which the wipers first sweep are indicatedin full lines and are swept by the ends of the wipers shown in full lines and the arcs over which the wipers sweep after traversing the full line arcs are indicated in broken lines and are swept by the ends of the wipers shown in broken lines. a The wipers are'denoted by the characters P and M for the negative'and positive line wire wipers, the test and holding wire wipers and the marking wipers respectively, a numeral indicating the wipers associated with arcs of contacts of a particular group of one hundred The selector is driven by an individual the driving mechanism, being represented generally by the magnet- MU. There are two ofinormal contacts 'NI and N2 operated when the wipers leave the position atthe commencement of the bank on which they normally rest. The

normal contacts in the bank are not connected to-outlets,'outlets from the selector being connected to the next 50 contacts. 'tact'is a last contact position and is commoned The 52d conin the two pairs of test arcs to the 52d contacts in thebroken line arcs and connected to a last contact relay LC; Commonedcontactsinsimilar positions in the Wire arcs are connected for the operation of overflow meters and commoned contacts in similar positions in the marking arcs are-connected to the test relay in thecommon control circuit. These latter contacts are also commoned to the first contact in the broken line are of wiper Mi. The first contact in the broken line are of wiper PI is adapted to be connected in the common control circuit to a relay for restoring certain circuits following a preliminary rotation of the wipers to this contact position,

hereinafter referred to as the predetermined con-- tact position. The selector also includes the coupling relay K for coupling it to the common control circuit serving it, the switching relay H, and wiper switching relay WS.

The group selector is adapted to be taken into use by two values of the same digit, say, an odd value and an even value and therefore carries tralhc for lines designated by two different values of the same digit. 'Trafiic in respect of one digital value is routed over contacts in the full line arcs and traffic in respect of the other digital value is routed over contacts in the broken line arcs. Also, the outlets from the switch carry trafiic for linesdesignated by two different values of the digit appropriate to the preceding switching stage, one of which may be an odd value and the other an even value. Difierentiation between the two digital values of the digit appropriate to the preceding switching stage is effected inthe'common control circuit by arranging that in 'response to a signal from the preceding switching stage difierent stepping switches for :rnarking purposes are taken into use for the two values, one for the odd value, and'one for the-even value of a. pair by which the group selector illustrated may be selected. Similarly, differentiation between the two values of the digit received at the group selector is eflected in the common control circuit and a signal is transmitted to the succeeding switching stage. The signal, in the present example, is the connection of earth to the wire when the connection is switched through at the particular switching stage and its efiect is to prevent a relayin the succeeding stage from operating. In the absence of the signal the .re: lay operates at the time the selector is seized and brings about a preliminary rotation of the selector wipers to-thepredetermined contactposition.

The common control circuit includes the low .impedanceimpulse receiving relay A, release relay B and its auxiliaries BA and BB, slow releasing dialling relay C, thigh speedtest relay T and its auxiliary TA, last-contact relay LC, the rela P for determining whether the signal diiierentiating the two values of the digit by which the associated group selector may be seized has been transmitted or not and its auxiliaries PA and PP. Relay PA is used as a steering relay to direct repeated impulses to one or other of two marking devices, in the present example stepping switches, and to connect up the several banks of one or other. 'of the two stepping switches. There is also a relay S, slow to release,

which is concerned with reverting a signal if a dead number is received at the group selector and with the-search oian outlet group that may be connected in two like arcs of the group selector, e. g. the full line arcs in both sets, or the broken line arcs in both sets. There is also a high impedance relay AA over which balanced tone signals may be reverted and which permits the use of a low impedance impulse receivingrelay.

There are two stepping switches MA andMB each having 8 wipers and banks. Their magnets are designated MAM and MBM and each has an armature-operated contact maon and mbon respectively. Switch MA is concerned withoutlets'connected in the full line-arcs of the selector and switchMBis concerned with outlets connected inthe broken :line arcs of the selector. Their wipers are connected pairs, the banks 'of wipers l beingoff-normal-banks, those of wiper 2 being concerned with the transmission forward of the differentiating'signaL thoseof wipers 3 and 4 being marking. banks, those of wipers 5 and 6 being concerned with wiper switching and those of wipers I and 8being connected to overflow meters. The common control circuit is adapted to operate in conjunction with group selectors of two numerical groups and with the exception of the wipers and banks of the stepping switches numbered I and 2, one wiper and bank of a pair is concerned with group selectors in one numerical group and the other wiper and bank of the pair is concerned with group selectors in the other numerical group. The selector illustrated is assumed to be one in the numerical group I and its connections to the control circuit are shown in full, while connections for the control group selectors in the other numerical group where these are not commoned with those for group selectors of numerical group I are designated NG2.

' The group selectors of the numerical group 2 are identical to the group selector shown in Fig. 1. Calls to group selectors of numerical group 2 are routed over different paths than calls to group selectors of numerical group I in well known manner. Calls thru the bank contacts .of group selectors of numerical group 2 are routed to different points than calls thru the bank contacts of the group selectors of numerical group I. The ten marking leads provided for the contacts associated with wipers such as MI and M2 of Fig. 1 may be connected in any desired manner in the bank contacts shown in solid lines and also in any desired manner in the bank contacts shown in broken lines and multipled to similar contacts in the banks of each of the group selectors of the group. These ten =marking leads may be connected in any desired manner inthe-bank contacts'associated with the wiper .MA3 (Fig. 2) and also in any desired manner in the bank contacts associated with the wiper MB3. The normal or operated'condition of relay PA determines whether the marking thru wiper MA3 or 1VB3 will be efiective and the normal or'operatedcondition of relay PP determines whether the bank contacts shown in' solid lines or broken lines will be used. In the same way the marking leads designated NGZ are connected. at the bank'contacts associated with the wipers MI and M2 of the group selectors of numerical groupz2 and at the bank contacts associatedwith the wipers MA4 and MR4. It maybe-seen that each time a marking is extended from the common control equipmentto the group selectors ofnumerical group I a marking is also extended to the group selectors of numerical group 2. However, as the K relay of only one of the group selectors controlled by the common control equipment -.(Fig. 2) c'an'be operatedatlany one time the operating groupselector will test'only for the marking extended to the numerical group to which it belongs.

" A detailed description will now be given of the operation of the group selector and the common control circuit.

-The selector and common. control-circuit; test free by reason of the batteryconnection to "wire 10 over wipers MAZ and MBZ at normal, contacts bat and N2.. Contacts 'ba2-ba8 are included in the test-in circuits for seven other selectors served by the same common control circuit. When the selector is takeninto use, relay A is operated and relay P may or may not'be operated in series with it. If a discriminating condition is applied at the preceding selecting stage,- earth will be present on the positive wire at this time and. relay a I 6 a P willbe'short-circuited, the circuit for relay A then being from this earth over contacts M and let. If the differentiating earth is not present, relay P will be operated in a circuit from earth over its left hand winding, contacts Z02 and 11.3 and the preceding loop in series with relay A. When relay A operates, contact al closes a circuit for relay B over resistance YA, contact pa3 and magnet MAM. Relay B operates but the magnet does not operate in this circuit and contact bl closes circuits for relays BA and BB and lights the supervisory lamp SL. Contact 122 applies earth over the loop for relay A independently of that over relay P or the earth connected to the wire at the preceding switching stage and prevents operation of relay P in series with relay A when the signalling earth is disconnected. Contact b3 connects battery to relay K which operates to the earth applied to wire 10 in the preceding circuit, contact b4 closes a circuit from earth over wipers MB! and MAI at normal for the left-hand winding of relay C, contact 125 prepares a holding circuit for relay C during impulsing and contact b6 closes a circuit for starting the tone generator. Relay BA on operation opens all the test-in circuits and relay BB at contacts bbl and bb2 opens the homing circuits for the stepping switches and closes points in the test circuit and the circuit for magnet MU of the group selector. Relay C operates and at contact cl prepares an operating circuit for magnet MAM by shunting resistance YA by the low resistance winding of relay C by means of which this relay is held during impulsing. Contact c2 opens a point in the circuit for magnet MU to guard against its operation during impulse reception. Relay K operates and locks up at contact is! applies a guarding earth to the holdmg wire p at contact k2, connects the wire tocontacts in the banks of wiper MA2 and MB2 at contact k3, closes a point in the operating circuit of relay H at contact k4 anda point in the operating circuit of relay WS at contact k5, connects up magnet MU at contact is and the test 5 'circuit'at contact 701.

wipers of the stepping switches from wipers MA3 and-MAA to wipers MB3 and M134, contact 'pa3 substitutes magnet MBM for magnet MAM and contacts pad and gnu-5 change over the connections of wipers 1 and 8 of switch MA tothose of switch MB in the circuit of overflow meters to correspond with the connections made over contact 10:12. Contact 0 02 connects the right-hand winding of relay PP to the predetermined contact in the arc of wiper Pl, contact 12173 closesa circuit for magnet MU and a test circuit independently of relay C, contactpp l disconnects earth from theleft-hand winding of relay S, contact 21196 disconnects the normal marking circuit and contact pp! disconnects relay LC. consequent on the changeover of contact 12123 earth is con: nected over contacts tl, tal and 706 to magnet MU and over rectifier MBA and both windings of. relay TIv in seriesto the contact in the prede-v termined p s tion. i the. ba of w p r- M Magnet Miloperates and the selector wipers are:

magnet MU and the right-hand winding of relay.

PP becomes energized in the test circuit. The

twowindinss of relay. PP are connected in opposition so that therelay is released and the test circuit is opened releasing relay- T. Contact p113 re-imposes the short circuit about winding (1) ofrelay TA; and the points opened at contacts; ppl, p396' and, pp"! are closed. Relay PA remains lockedup.

When impulses are received, relay A will respend and-at contact a] repeat them in a circuit from; earth over contacts b5, al, low-resistance winding of relay C, contacts cl and pa3 to which- GVGI fthe two magnets is connected up. The stepping switch magnet operates and steps the switch inaccordance with the number of ime pulses received. As soon as the switch takes its first step the operating circuit for relay C is opened at-wiper I of the stepping switch. Relay Q- remains operated during the continuance of impulse repetition by means of the repeated impulses. to thestepping switch magnet and by reason of its; copper slug and. after the last impulse of a train whenrelay A remains steadily operated relay- C releases, the resistance of relay B being too high for it. toholdin series with the latter relay. Contact. 02 closes and a circuit is closed from earth over wiper MBI at normal, wiper MAI ofi-normal and contact hi)! or over wiper MB !v elf-normal and contact bb2, thence over 7 contacts 02, ti, tcii and k6 for magnet MU and the selector is driven in search of a free outlet in. the. group marked by the operated stepping switch. The outlets oft-he group to be searched, ifconnected in the full line arcs of the selector will bemarked over wiper MA3 with relay PA unoperated and if connected in the broken line arcs oftheselector the group will be marked over wiper MBsw-ith relay PA operated, the search by the selector starting at thenormal contact position in the, former case and at the predetermined contact position in the latter case. Wipers MA4 and MB4 areused for marking outlet groups in selectors of another numerical group and the connections between their banks and the marking arcs of-theselectors of the other numerical group may. differ from those for the selector of the group illustrated.

When a free outlet in the marked group is foundby the selector, relay T is operated from earth over. the previously traced circuit to contact c2, thence over rectifier MRA, both windings of the relay. in series, contacts ppfi and paZ, the marking wiper connected up. by relay PA, connection'tothe, marking arc of the selector, marking, wiper, contacts, 7.08.5, kl, wsd, test wiper to battery onfthe test wire outlet. Contact ti changes over, busying the outlet by shunting the high resistance left-hand winding of relay T and stopping the selector by switching winding (1) of relay TA in series in the circuit of magnet MU. Magnet MU will not hold in series with relay TA so that it releases and stops the switch. Relay TA operates and opens a further point in the circuit for magnet MU at contact tal, operates relay H at contact to! and at contact m3 connects earthto wiper MB2,or if'switch MA has, been used, to wiper Relay H operates andlocks up over its two windings in series and, contact hl to the earth on wire p and at contact.

hZextendsthis earth to the test outlet to engage the seized circuit and at the same time release relay- T byshort-circuit. Contacts b3 and M.

switch through the speaking wires and contact hB'earths wire q to operate a relay in a feeding bridge circuit if one precedes the group selector, for switching ina feeding bridge as described in United States Patent No. 1,971,501 granted August 28, 1934', to W. H. Grinsted et al. The operating winding of relay H is of high resistance and the right-hand winding which is connectedin. series. with; it is of higher resistance sothat when the holding earth is removed from wire-p.

at the end of, a conversation there will be no danger of a. test. relay in a selector that happens. to be testing in to: one of the, selectors that are: about to release operating in series with a numberswitch concerned anditerminal ye so that earthv over contact: bl and this connection will be extended over. contact 105 to relay WS and that relay will be operated. Contacts wsZ-wsiii change over the connections from the odd-numbered to the even-numbered wipers of the selector so that search willbe controlled over wipers M2 and P2 andaon-the eventualoperation of relay H relay; WS will lockup over contacts wsl, h5 and Ni. Suitable cross connections would be made be-. tween terminal yzand the banks of wipers 6 of the two stepping switches for wiper switching purposes in selectors of the other numerical group. It. will be appreciated that, by the use of two stepping switches or two diiierentbanks of asinglesteppin switch, wiper switching may take :placexin responsetoa digital value received at the selector when theselector has been seized tothee same-digital, value received when the selector has heemseized inrespect of the other digital value. of the; pain The use.-oftwo, steps ping switches, however, allows different wiper switching connections: in. two different numerical groups of selectors. Consequent on the operation of relayH; relay A is released at contacts h3' and h t and atcontactal, short-circuits relay B. After an intervalrelay B releases, releasing relays BA", BB, and P if operated and extinguishing thelamp SL at contact bl, releasing relay K at. contact 113 and: opening. points in the op.- erating circuits of relay C andthe stepping switch magnets atcontacts b45and 795 respectively. On the release. of. relay-BB the homing circuit for thestepping switch used is. closed over its wiper off normal, contact of relay BB; magnet-operated contact of the switch and the switch magnet and the steppingswitch is homed' in known manner. Release ofrelayP releases relay PA-at contact: p2: and relay TA is. released at a contact-:of-relay BB. Release of relay BA re-closes points in the test-incircuits for the associated selectors. this circuit. being completed on the homing of the stepping switch. 1

It has been assumed that all the outlets of a group will .beconnected in onearc of the selector. As however, 50 is not. an integral multiple of 20, and 10 isithe usual. number of groupsto be catered for, either the groups must vary insize or, if groups of outlets each are required,

some of the outlets of one group must be con- ;nected in one arc and the remainder in another.

The group selector illustrated caters for such an arrangement and allows the first 10 outlets of a group to be connected to the first 10 outlet positions in an even numbered arc and the remaining 10 outlets to be connected to the last 10 outlet positions in the corresponding odd numbered arc. The marking arcs in the selector banks would-be cross-connected to the marking banks of the stepping switches accordingly and the search of such a group of outlets would then take place as follows. When the first impulse is received, relay C will be in an operated condition and earth over wiper of the stepping switch responding to impulses will be extended over contacts of relay BB and front contact 02 to relay 3. 'Relay S operates and at contact s3 connects earth over contacts bl and 12104 to terminal sg. In the position to which the stepping switch is the connection from the odd-numbered wipers to the even-numbered wipers. At the end of the impulse train relay C releases and the search commences. If a preliminary rotation of the selector had been required, it would have taken place before the release of relay C. Relay S is slugged to allow it to maintain its contacts operated for a time suflicient to allow the selector wipers to 'pass'over the first 10 contacts in the bank but the relay will release before the th contact is reached. If none of the first 10 outlets is found free, the selector is continued in motion until the 40th contact is reached and search then continues over the last .10 outlets in the oddnumbered arcs, relay S having released by this time and released relay WS. If one of the outlets of the marked group is found free, operations take place in the manner already described but from relay T over thelast contacts and wipers in the arcs of wipers MI' and PI, contact pp! and the'shunt-across winding (II) of relay TA and relay LC. These two windings become energised in series with relay T but the two windings of relay TA are connected in opposition so that that relay does not now operate. Contacts Zcl and Z02 disconnect the loop circuit for relay A and substitute the high impedance relay AA, contact lc3 applies busy tone over wire BT and the right hand winding of relay AA whence it is induced over the other windings of the relay into the line and contact Z04 applies earth over contact k3, the +wire wiper, contact 10114 and wiper 1 of the stepping switch concerned for the operation of an overflow meter. Contact aal holds relay A. Battery and earth are applied alternately over wire BE, contact s2 and the +wire to give the well known flashing signal. By the inclusion of contact 10124 in the circuit over terminals sg and ya wiper switching is prevented during a prelminary movement of the selector. It will be seen therefore that a divided group of outlets -may be connected in either or both arcs of a pair. The operations described as taking place if no free outlet is found in a divided group'are exactly the same as those that will take place if no free outlet is found in any group. 5 r.

It will be remembered that when a stepping switch leaves its normal position, relay 3. is op:- erated. Terminal s is connected to contacts in the banks of wipers 5 and 6 of the stepping switches corresponding to dead numbers and if one of these is called, earth over contacts bl and 10304 is extended over the left-hand Winding of relay S, terminal s, the bank contact and wiper of the stepping switch concerned-and contact led to relay WS. The selector wipers are driven to the last contacts in the arc in which the selector is stopped and relay LC- is operated. Relay A is disconnected and relay AA comiected to the calling loop, earth'being connected over contact 82 and the middle winding of the-relay. QN.:U. tone is fed over contacts sl and Z03 to the' right hand winding whence it is repeated by induction cver'the two other windings of the relay and the calling loop.

When the caller clears under busy or dead number conditions relay AA is released and .in

turn releases relay A which brings about therelease of the common control circuit in the manner before described.

When the caller clears after a conversation, earth is disconnected from wire p at the point from which the connection is held and relay I-I releases. The through circuit is disconnected at contacts hl, h2, b3 and M and contact 71.5 releases relay WS if this relay has been operated and closes the homing circuit over contacts NI and k6 for magnet MU; Contacts h6 disconnects earth from wire q. The selector wipers are r0- tated to their normal position in which the circuit of magnet MU is opened at contacts NI.

C0ntacts N2 close in the test-in circuit and the selector is again in a condition for further. use.

For the differentiation between-.twovalues of the digit which may result in selection of an .outlet in the same group," earth is connected, when an outlet is seized, to the wire over contact ta3, wiper 2 of the stepping switch concerned and contact k3 for-evenvalues of the digit and this prevents operation at the next switching stage of a relay corresponding to relay P herein or efiects some other differentiating action.. The signal is disconnected on the release of relay TA. If the digit has anodd value, the earth is not connected and relay action will take place at the succeding switching stage. If the differentiating arrangements at the succeding switching stage are suitable, it may be arranged for action to take place when the wire is earthed and not when it is not earthed as described.

I claim:

1. In an automatic telephone system, a selector switch, two main groups of lines, sub groups of lines in each of said main groups, a pair of marking devices one for each main group, a plurality of marking leads, means including said marking leads for connecting one of said marking devices to the sub groups of lines in one of said main groups and for connecting the other of said marking devices to the sub groups of lines in the other of said main groups, means in the switch responsive to a received signal for selecting a particular marking device of one main group and means in the switch responsive to a series of impulses for operating the particular marking clevice to thereby mark a sub group only in the main group of the selected marking device.

2. In an automatic telephone system, a selector switch having two sets of wipers, each set ofwipers having access-to -a plurality of'maingroups of lines each-divided-into sub groups, a pair of marking devices one for one main group of both wiper sets and the other for the other main group of lines'of both wiper sets, means for connecting ;said marking devices "to their respective main groupsof lines, means'inthe switch responsive to areceived signal for electing one-of the main groups of each wiper set by selecting one of the marking devices and means in the switch responsive-toareceived series of impulsesfor then operating the selected marking device to thereby "mark'a trunk inonly one main group and means controlled bytheselected marking device for selecting one of the two sets of wipers to be used --for selecting a line in the selected main group.

3. In an automatic telephone system, selector switches of one numerical group having access to-main and sub groups of lines-selector switches "oi -another numerical group having access to other main and sub groups of lines, a common control equipment for controlling the operation of the switches of said one numerical group and the switches of said other numerical group, means for connecting a switch of either numerical group to said control equipment, a:pair of marking devices insaid control equipment, means in said equipment responsive .to .a signal received by a connected switch for selecting a particular marking deviceand meansresponsive to received impulses tooperate the selected marking device to thereby mark a sub group of lines in one main group accessible to theswitches of said one nu- :mercial group and to mark a sub group of lines in one main-groupaccessible to the switches of said-other numerical group, and means in aconnected-s'witch for rendering effective the mark :for thesub groupof lines accessible to the switch- -es.of the numericalgroup to which the connected switchbelongs.

'4. .A selector :switch such as claimed in claim :2 having also means whereby the wipers are stepped to a predetermined position responsive tosaid received signal to prepare the switch for selecting aline only .in one main group and be- %fore the marking devices are operated.

5. in a telephone system, a first'group of selectorswitches, a second group of selector switches, :control equipment, means. for connecting said equipment to a selector of said first group, means for connecting said equipment to a selector of said .second .group, a pair of marking devices in said control equipment, means .-f.or selecting one of said marking devices, means for operating a selectedone of said marking devices, means in cluding an operated marking device for extending a marking to the switches of saidfirst group and for extending a marking to the switches of said second group,-and means in aselector to which said-equipment is connected for rendering effective-the marking extended to the group of switches in which said last mentioned selector is included.

6. In a, selector switch,*a first wiper set,'a second wiper set, outlets for each wiper set, operating means for simultaneously moving said wiper sets .over their respectiveoutlets, conductors, a wiper switching relay having a normal position andan operated position, means for 'connectingsaid conductors to said first wiper set with said wiper switching'relay in its normal position-means for connecting "said conductors to :said :second wiper set with said wiper switchingtrelay operated, a

.marking device, a'relay, a circuitfor said .relay, :control means for operating'said device and for completing said circuit .to operate said relay, means including said device and said relay for operating said wiper switching-relay to connect said conductorsto said second wiper set, said control means efiective after operating said device and "said relay for controlling said operating means to move said wiper sets over said outlets and to open said circuit to said relay, means for releas- :ing said relay a predetermined time after the movement of said wiper sets is-started, and means responsive to the release of said relay for releasing-said wiper switching relay toits normal .position toconnect saidconductors to said first-wiper set.

DOUGLAS PERCY LONG.

REFERENCES CITED The ioll'owing references are of record in the file of this patent:

UNITED STATES PATENTs Long Feb. 18, 1947 

